Statistical analysis The first aim of this retrospective analysis will be to evaluate the possible role of these investigated gene polymorphisms to predict the bevacizumab response in terms of PFS. The secondary end-points will be the correlations with overall survival (OS) and response rate. All polymorphisms will be analyzed for deviation from the Hardy-Weinberg Equilibrium (HWE) by means of comparison between observed allelic distributions with those expected from the HWE by on χ2 test. Any correlation between gene polymorphisms and response rate will be analyzed by the two-sided Fisher's Exact Test. The association between each individual polymorphism and the most relevant clinical-pathological characteristics with PFS will be tested using a Cox proportional hazards model. The Multifactor Dimensionality Reduction (MDR) methodology will be applied (using version 2.0 beta 6 of MDR software available on http://sourceforge.net/projects/mdr/) to investigate the role of an interaction between gene polymorphisms in identifying biomarkers of paclitaxel plus bevacizumab response.